This invention generally relates to an improved refrigeration compressor with electronic control arrangement and, in particular to a reciprocating, hermetic-type compressor for domestic refrigerators and freezers.
Currently, this type of compressor is provided with an electric induction motor operating under an on-off type of control at such rotational rates of speed as determined by the existing electric line frequency, i.e. 50 Hz or 60 Hz.
Under these conditions, the refrigerating capacity, given that an equal amount of refrigerant fluid used, is therefore determined mainly by the displacement, i.e. swept volume, of the compressor. Furthermore, it should be noted that, even when adding a running capacitor, the efficiency of an induction motor does not exceed a value of 0.8.
It should also be noted that the penetration rate of combined refrigeration appliances with separate fresh-food and frozen-food compartments served by a single refrigerating circuit with a single compressor is continuously increasing. In view of their ability to cope with the energy demand peaks resulting in connection with the need of freezing the maximum allowable load of food in the corresponding freezing compartment, these appliances must be equipped with a correspondingly rated compressor, i.e. a compressor having a higher power rating than normally required for regular operation, adequately sized to suit the highest energy demand for freezing. Consequently, when the appliance is operating normally in view of only lowering the temperature in the fresh food compartment, the compressor actually turns out to be overrated, i.e. oversized, and uses a considerable amount of energy due to the repeated, frequent cycling of the compressor.
As is widely appreciated, energy savings through the efficiency of household appliances is a primary goal of appliance manufacturers, who have been imposed well-defined energy consumption limits in several countries and are therefore confronted with the need of keeping below these limits.
Finally, a further requirement in connection with all types of appliances intended for home use comes from the need to reduce the operating noise of such appliances as much as possible.